The present invention relates to apparatus for stripping electrical insulation from the end of a ribbon cable, more particularly to precision apparatus for removing the outer insulation from ribbon cable having a foil shield.
The term ribbon cable is generally applied to a plurality of side-by-side conductors embedded in a common body on insulation. The relatively close control of conductor spacing lends such cable readily to mass termination to insulation displacing terminals having centerlines spaced as the conductors. In recent years data transmission applications have led to the development of shielded cable having a foil shield around the ribbon cable, which shield is in turn surrounded by a common body of outer insulation. Such cable is commonly manufactured by running the ribbon cable and a drain wire through a die which forms the foil shield thereagainst in a "cigarette wrap" configuration, and subsequently through an extrusion die where PVC insulation is extruded against the foil to form the outer insulation. The foil shield is actually a laminate of foil and polyester film, with the polyester film facing outward against the PVC.
U.S. Pat. No. 3,774,478 describes an apparatus for stripping insulation from the end of a ribbon cable. Cutting blades mounted on opposite sides of a cable support are arranged to move on arcuate paths toward opposite planar sides of the cable, the blades having parallel rectilinear edges which penetrate the insulation. The cable is then pulled from the closed blades, leaving a single slug of insulation. While this tool is well suited to stripping ordinary ribbon cable, problems arise when it is used with shielded cable. Play in the linkage which effects arcuate movement of the blades makes it difficult to adjust for effective insulation penetration without nicking the foil shield. Since the insulation is pulled off in a single tubular slug, it is sufficiently adhered to the shield to tear it free if the shield is nicked. Since it is desirable to consistently keep the exposed shield intact with the shield in the unstripped portion of cable for termination purposes, a more specilized tool would be desirable.